NEWS

   1 Bison News
   2 ----------
   3
   4 Changes in version 1.49b:
   5
   6 * Undefined token
   7   The undefined token was systematically mapped to 2 which prevented
   8   the use of 2 from the user.  This is no longer the case.
   9
  10 * Unknown token numbers
  11   If yylex returned a code out of range, yyparse could die.  This is
  12   no longer the case.
  13
  14 * Error token
  15   According to POSIX, the error token should be numbered as 256.
  16   Bison extends this requirement by making it a preference: *if* the
  17   user specified that one of her tokens is numbered 256, then error
  18   will be mapped onto another number.
  19
  20 * Large grammars
  21   Large grammars are now supported (large token numbers, large grammar
  22   size (= sum of the LHS and RHS lengths), large LALR tables).
  23
  24 * Explicit initial rule
  25   Bison used to play hacks with the initial rule, which the user does
  26   not write.  It is now explicit, and visible in the reports and
  27   graphs as rule 0.
  28
  29 * Useless rules
  30   Before, Bison reported the useless rules, but, although not used,
  31   included them in the parsers.  They are now actually removed.
  32
  33 * Incorrect `Token not used'
  34   On a grammar such as
  35
  36            %token useless useful
  37            %%
  38            exp: '0' %prec useful;
  39
  40   where a token was used to set the precedence of the last rule,
  41   bison reported both `useful' and `useless' as useless tokens.
  42
  43 * Revert the C++ namespace changes introduced in 1.31
  44   as they caused too many portability hassles.
  45
  46 * Default locations
  47   By an accident of design, the default computation of @$ was
  48   performed after another default computation was performed: @$ = @1.
  49   The latter is now removed: YYLLOC_DEFAULT is fully responsible of
  50   the computation of @$.
  51
  52 * Token end-of-file
  53   The token end of file may be specified by the user, in which case,
  54   the user symbol is used in the reports, the graphs, and the verbose
  55   error messages instead of `$', which remains being the defaults.
  56   For instance
  57      %token YYEOF 0
  58   or
  59      %token YYEOF 0 "end of file"
  60
  61 * Semantic parser
  62   This old option, which has been broken for ages, is removed.
  63
  64 * New translations
  65   Croatian, thanks to Denis Lackovic.
  66
  67 * Incorrect token definitions
  68   When fed with `%token 'a' "A"', Bison used to output `#define 'a' 65'.
  69
  70 * Token definitions as enums
  71   Tokens are output both as the traditional #define's, and, provided
  72   the compiler supports ANSI C or is a C++ compiler, as enums.
  73   This helps debuggers producing symbols instead of values.
  74
  75 \f
  76 Changes in version 1.35, 2002-03-25:
  77
  78 * C Skeleton
  79   Some projects use Bison's C parser with C++ compilers, and define
  80   YYSTYPE as a class.  The recent adjustment of C parsers for data
  81   alignment and 64 bit architectures made this impossible.
  82
  83   Because for the time being no real solution for C++ parser
  84   generation exists, kludges were implemented in the parser to
  85   maintain this use.  In the future, when Bison has C++ parsers, this
  86   kludge will be disabled.
  87
  88   This kludge also addresses some C++ problems when the stack was
  89   extended.
  90
  91 \f
  92 Changes in version 1.34, 2002-03-12:
  93
  94 * File name clashes are detected
  95   $ bison foo.y -d -o foo.x
  96   fatal error: header and parser would both be named `foo.x'
  97
  98 * A missing `;' at the end of a rule triggers a warning
  99   In accordance with POSIX, and in agreement with other
 100   Yacc implementations, Bison will mandate this semicolon in the near
 101   future.  This eases the implementation of a Bison parser of Bison
 102   grammars by making this grammar LALR(1) instead of LR(2).  To
 103   facilitate the transition, this release introduces a warning.
 104
 105 * Revert the C++ namespace changes introduced in 1.31, as they caused too
 106   many portability hassles.
 107
 108 * DJGPP support added.
 109
 110 * Fix test suite portability problems.
 111 \f
 112 Changes in version 1.33, 2002-02-07:
 113
 114 * Fix C++ issues
 115   Groff could not be compiled for the definition of size_t was lacking
 116   under some conditions.
 117
 118 * Catch invalid @n
 119   As is done with $n.
 120 \f
 121 Changes in version 1.32, 2002-01-23:
 122
 123 * Fix Yacc output file names
 124
 125 * Portability fixes
 126
 127 * Italian, Dutch translations
 128 \f
 129 Changes in version 1.31, 2002-01-14:
 130
 131 * Many Bug Fixes
 132
 133 * GNU Gettext and %expect
 134   GNU Gettext asserts 10 s/r conflicts, but there are 7.  Now that
 135   Bison dies on incorrect %expectations, we fear there will be
 136   too many bug reports for Gettext, so _for the time being_, %expect
 137   does not trigger an error when the input file is named `plural.y'.
 138
 139 * Use of alloca in parsers
 140   If YYSTACK_USE_ALLOCA is defined to 0, then the parsers will use
 141   malloc exclusively.  Since 1.29, but was not NEWS'ed.
 142
 143   alloca is used only when compiled with GCC, to avoid portability
 144   problems as on AIX.
 145
 146 * When the generated parser lacks debugging code, YYDEBUG is now 0
 147   (as POSIX requires) instead of being undefined.
 148
 149 * User Actions
 150   Bison has always permitted actions such as { $$ = $1 }: it adds the
 151   ending semicolon.  Now if in Yacc compatibility mode, the semicolon
 152   is no longer output: one has to write { $$ = $1; }.
 153
 154 * Better C++ compliance
 155   The output parsers try to respect C++ namespaces.
 156   [This turned out to be a failed experiment, and it was reverted later.]
 157
 158 * Reduced Grammars
 159   Fixed bugs when reporting useless nonterminals.
 160
 161 * 64 bit hosts
 162   The parsers work properly on 64 bit hosts.
 163
 164 * Error messages
 165   Some calls to strerror resulted in scrambled or missing error messages.
 166
 167 * %expect
 168   When the number of shift/reduce conflicts is correct, don't issue
 169   any warning.
 170
 171 * The verbose report includes the rule line numbers.
 172
 173 * Rule line numbers are fixed in traces.
 174
 175 * Swedish translation
 176
 177 * Parse errors
 178   Verbose parse error messages from the parsers are better looking.
 179   Before: parse error: unexpected `'/'', expecting `"number"' or `'-'' or `'(''
 180      Now: parse error: unexpected '/', expecting "number" or '-' or '('
 181
 182 * Fixed parser memory leaks.
 183   When the generated parser was using malloc to extend its stacks, the
 184   previous allocations were not freed.
 185
 186 * Fixed verbose output file.
 187   Some newlines were missing.
 188   Some conflicts in state descriptions were missing.
 189
 190 * Fixed conflict report.
 191   Option -v was needed to get the result.
 192
 193 * %expect
 194   Was not used.
 195   Mismatches are errors, not warnings.
 196
 197 * Fixed incorrect processing of some invalid input.
 198
 199 * Fixed CPP guards: 9foo.h uses BISON_9FOO_H instead of 9FOO_H.
 200
 201 * Fixed some typos in the documentation.
 202
 203 * %token MY_EOF 0 is supported.
 204   Before, MY_EOF was silently renumbered as 257.
 205
 206 * doc/refcard.tex is updated.
 207
 208 * %output, %file-prefix, %name-prefix.
 209   New.
 210
 211 * --output
 212   New, aliasing `--output-file'.
 213 \f
 214 Changes in version 1.30, 2001-10-26:
 215
 216 * `--defines' and `--graph' have now an optionnal argument which is the
 217   output file name. `-d' and `-g' do not change, they do not take any
 218   argument.
 219
 220 * `%source_extension' and `%header_extension' are removed, failed
 221   experiment.
 222
 223 * Portability fixes.
 224 \f
 225 Changes in version 1.29, 2001-09-07:
 226
 227 * The output file does not define const, as this caused problems when used
 228   with common autoconfiguration schemes.  If you still use ancient compilers
 229   that lack const, compile with the equivalent of the C compiler option
 230   `-Dconst='.  autoconf's AC_C_CONST macro provides one way to do this.
 231
 232 * Added `-g' and `--graph'.
 233
 234 * The Bison manual is now distributed under the terms of the GNU FDL.
 235
 236 * The input and the output files has automatically a similar extension.
 237
 238 * Russian translation added.
 239
 240 * NLS support updated; should hopefully be less troublesome.
 241
 242 * Added the old Bison reference card.
 243
 244 * Added `--locations' and `%locations'.
 245
 246 * Added `-S' and `--skeleton'.
 247
 248 * `%raw', `-r', `--raw' is disabled.
 249
 250 * Special characters are escaped when output.  This solves the problems
 251   of the #line lines with path names including backslashes.
 252
 253 * New directives.
 254   `%yacc', `%fixed_output_files', `%defines', `%no_parser', `%verbose',
 255   `%debug', `%source_extension' and `%header_extension'.
 256
 257 * @$
 258   Automatic location tracking.
 259 \f
 260 Changes in version 1.28, 1999-07-06:
 261
 262 * Should compile better now with K&R compilers.
 263
 264 * Added NLS.
 265
 266 * Fixed a problem with escaping the double quote character.
 267
 268 * There is now a FAQ.
 269 \f
 270 Changes in version 1.27:
 271
 272 * The make rule which prevented bison.simple from being created on
 273   some systems has been fixed.
 274 \f
 275 Changes in version 1.26:
 276
 277 * Bison now uses automake.
 278
 279 * New mailing lists: <bug-bison@gnu.org> and <help-bison@gnu.org>.
 280
 281 * Token numbers now start at 257 as previously documented, not 258.
 282
 283 * Bison honors the TMPDIR environment variable.
 284
 285 * A couple of buffer overruns have been fixed.
 286
 287 * Problems when closing files should now be reported.
 288
 289 * Generated parsers should now work even on operating systems which do
 290   not provide alloca().
 291 \f
 292 Changes in version 1.25, 1995-10-16:
 293
 294 * Errors in the input grammar are not fatal; Bison keeps reading
 295 the grammar file, and reports all the errors found in it.
 296
 297 * Tokens can now be specified as multiple-character strings: for
 298 example, you could use "<=" for a token which looks like <=, instead
 299 of chosing a name like LESSEQ.
 300
 301 * The %token_table declaration says to write a table of tokens (names
 302 and numbers) into the parser file.  The yylex function can use this
 303 table to recognize multiple-character string tokens, or for other
 304 purposes.
 305
 306 * The %no_lines declaration says not to generate any #line preprocessor
 307 directives in the parser file.
 308
 309 * The %raw declaration says to use internal Bison token numbers, not
 310 Yacc-compatible token numbers, when token names are defined as macros.
 311
 312 * The --no-parser option produces the parser tables without including
 313 the parser engine; a project can now use its own parser engine.
 314 The actions go into a separate file called NAME.act, in the form of
 315 a switch statement body.
 316 \f
 317 Changes in version 1.23:
 318
 319 The user can define YYPARSE_PARAM as the name of an argument to be
 320 passed into yyparse.  The argument should have type void *.  It should
 321 actually point to an object.  Grammar actions can access the variable
 322 by casting it to the proper pointer type.
 323
 324 Line numbers in output file corrected.
 325 \f
 326 Changes in version 1.22:
 327
 328 --help option added.
 329 \f
 330 Changes in version 1.20:
 331
 332 Output file does not redefine const for C++.
 333
 334 Local Variables:
 335 mode: outline
 336 End:
 337
 338 -----
 339
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 341
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